[codex] Update SaC inspect guidance

[realmorrisliu]

Summary

• Add restrained guidance for choosing sheet-range, semantic style evidence, and conditional-formatting evidence surfaces.
• Document SAC_UNIT_STATE_DRIFT recovery choices and keep materialize recovery separate from materialize archives.
• Add concise recipes for related range reads, conditional formatting inspection, and sheet-keyed-write usage.

Notes

• Did not add --format compact guidance because the add-compact-inspect-output OpenSpec task checklist is not closed.
• Kept guidance decision-oriented rather than making a mandatory agent workflow.

Validation

• npm run validate
• git diff --check